1 //===------- ItaniumCXXABI.cpp - AST support for the Itanium C++ ABI ------===// 2 // 3 // The LLVM Compiler Infrastructure 4 // 5 // This file is distributed under the University of Illinois Open Source 6 // License. See LICENSE.TXT for details. 7 // 8 //===----------------------------------------------------------------------===// 9 // 10 // This provides C++ AST support targeting the Itanium C++ ABI, which is 11 // documented at: 12 // http://www.codesourcery.com/public/cxx-abi/abi.html 13 // http://www.codesourcery.com/public/cxx-abi/abi-eh.html 14 // 15 // It also supports the closely-related ARM C++ ABI, documented at: 16 // http://infocenter.arm.com/help/topic/com.arm.doc.ihi0041c/IHI0041C_cppabi.pdf 17 // 18 //===----------------------------------------------------------------------===// 19 20 #include "CXXABI.h" 21 #include "clang/AST/ASTContext.h" 22 #include "clang/AST/DeclCXX.h" 23 #include "clang/AST/MangleNumberingContext.h" 24 #include "clang/AST/RecordLayout.h" 25 #include "clang/AST/Type.h" 26 #include "clang/Basic/TargetInfo.h" 27 28 using namespace clang; 29 30 namespace { 31 32 /// \brief Keeps track of the mangled names of lambda expressions and block 33 /// literals within a particular context. 34 class ItaniumNumberingContext : public MangleNumberingContext { 35 llvm::DenseMap<IdentifierInfo*, unsigned> VarManglingNumbers; 36 llvm::DenseMap<IdentifierInfo*, unsigned> TagManglingNumbers; 37 38 public: 39 /// Variable decls are numbered by identifier. 40 unsigned getManglingNumber(const VarDecl *VD, unsigned) override { 41 return ++VarManglingNumbers[VD->getIdentifier()]; 42 } 43 44 unsigned getManglingNumber(const TagDecl *TD, unsigned) override { 45 return ++TagManglingNumbers[TD->getIdentifier()]; 46 } 47 }; 48 49 class ItaniumCXXABI : public CXXABI { 50 protected: 51 ASTContext &Context; 52 public: 53 ItaniumCXXABI(ASTContext &Ctx) : Context(Ctx) { } 54 55 std::pair<uint64_t, unsigned> 56 getMemberPointerWidthAndAlign(const MemberPointerType *MPT) const override { 57 const TargetInfo &Target = Context.getTargetInfo(); 58 TargetInfo::IntType PtrDiff = Target.getPtrDiffType(0); 59 uint64_t Width = Target.getTypeWidth(PtrDiff); 60 unsigned Align = Target.getTypeAlign(PtrDiff); 61 if (MPT->getPointeeType()->isFunctionType()) 62 Width = 2 * Width; 63 return std::make_pair(Width, Align); 64 } 65 66 CallingConv getDefaultMethodCallConv(bool isVariadic) const override { 67 const llvm::Triple &T = Context.getTargetInfo().getTriple(); 68 if (!isVariadic && T.isWindowsGNUEnvironment() && 69 T.getArch() == llvm::Triple::x86) 70 return CC_X86ThisCall; 71 return CC_C; 72 } 73 74 // We cheat and just check that the class has a vtable pointer, and that it's 75 // only big enough to have a vtable pointer and nothing more (or less). 76 bool isNearlyEmpty(const CXXRecordDecl *RD) const override { 77 78 // Check that the class has a vtable pointer. 79 if (!RD->isDynamicClass()) 80 return false; 81 82 const ASTRecordLayout &Layout = Context.getASTRecordLayout(RD); 83 CharUnits PointerSize = 84 Context.toCharUnitsFromBits(Context.getTargetInfo().getPointerWidth(0)); 85 return Layout.getNonVirtualSize() == PointerSize; 86 } 87 88 MangleNumberingContext *createMangleNumberingContext() const override { 89 return new ItaniumNumberingContext(); 90 } 91 }; 92 } 93 94 CXXABI *clang::CreateItaniumCXXABI(ASTContext &Ctx) { 95 return new ItaniumCXXABI(Ctx); 96 } 97